Butterfly valve with improved shaft connection

Abstract

A butterfly valve is provided having a disc with a hub. The disc is adapted to be rotated between an open and a closed position. A valve seat is adapted to engage the disc in the closed position. A shaft has one end affixed to the hub and extends outwardly therefrom to permit torque to be transmitted to the disc from a point external thereof. The end of the shaft affixed to the hub includes a plurality of splines for securing the shaft to the hub. Each of the splines interfers with the hub by a maximum dimension of 0.030 inches. The hub has a stress that is less than 20,000 pounds per square inch. The shaft is joined to the disc by forming the valve disc with a portion of increased thickness (hub) relative to the main portion of the disc. The portion of increased thickness is formed adjacent the circumference of the disc. A hole is then machined into the portion of increased thickness parallel to the disc, with the hole having a diameter slightly smaller than the diameter of the shaft. Splines are formed on one end of the shaft and the shaft is then pressed into the hole, cutting grooves in the side walls of the hole, thereby forming a permanent connection between the shaft and the disc.

Dependencies are inferred from the claim text.